rhubarb-lip-sync/lib/webrtc-8d2248ff/webrtc/examples/objc/AppRTCDemo/ARDSDPUtils.m

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2016-06-21 20:13:05 +00:00
/*
* Copyright 2015 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#import "ARDSDPUtils.h"
#import "WebRTC/RTCLogging.h"
#import "WebRTC/RTCSessionDescription.h"
@implementation ARDSDPUtils
+ (RTCSessionDescription *)
descriptionForDescription:(RTCSessionDescription *)description
preferredVideoCodec:(NSString *)codec {
NSString *sdpString = description.sdp;
NSString *lineSeparator = @"\n";
NSString *mLineSeparator = @" ";
// Copied from PeerConnectionClient.java.
// TODO(tkchin): Move this to a shared C++ file.
NSMutableArray *lines =
[NSMutableArray arrayWithArray:
[sdpString componentsSeparatedByString:lineSeparator]];
NSInteger mLineIndex = -1;
NSString *codecRtpMap = nil;
// a=rtpmap:<payload type> <encoding name>/<clock rate>
// [/<encoding parameters>]
NSString *pattern =
[NSString stringWithFormat:@"^a=rtpmap:(\\d+) %@(/\\d+)+[\r]?$", codec];
NSRegularExpression *regex =
[NSRegularExpression regularExpressionWithPattern:pattern
options:0
error:nil];
for (NSInteger i = 0; (i < lines.count) && (mLineIndex == -1 || !codecRtpMap);
++i) {
NSString *line = lines[i];
if ([line hasPrefix:@"m=video"]) {
mLineIndex = i;
continue;
}
NSTextCheckingResult *codecMatches =
[regex firstMatchInString:line
options:0
range:NSMakeRange(0, line.length)];
if (codecMatches) {
codecRtpMap =
[line substringWithRange:[codecMatches rangeAtIndex:1]];
continue;
}
}
if (mLineIndex == -1) {
RTCLog(@"No m=video line, so can't prefer %@", codec);
return description;
}
if (!codecRtpMap) {
RTCLog(@"No rtpmap for %@", codec);
return description;
}
NSArray *origMLineParts =
[lines[mLineIndex] componentsSeparatedByString:mLineSeparator];
if (origMLineParts.count > 3) {
NSMutableArray *newMLineParts =
[NSMutableArray arrayWithCapacity:origMLineParts.count];
NSInteger origPartIndex = 0;
// Format is: m=<media> <port> <proto> <fmt> ...
[newMLineParts addObject:origMLineParts[origPartIndex++]];
[newMLineParts addObject:origMLineParts[origPartIndex++]];
[newMLineParts addObject:origMLineParts[origPartIndex++]];
[newMLineParts addObject:codecRtpMap];
for (; origPartIndex < origMLineParts.count; ++origPartIndex) {
if (![codecRtpMap isEqualToString:origMLineParts[origPartIndex]]) {
[newMLineParts addObject:origMLineParts[origPartIndex]];
}
}
NSString *newMLine =
[newMLineParts componentsJoinedByString:mLineSeparator];
[lines replaceObjectAtIndex:mLineIndex
withObject:newMLine];
} else {
RTCLogWarning(@"Wrong SDP media description format: %@", lines[mLineIndex]);
}
NSString *mangledSdpString = [lines componentsJoinedByString:lineSeparator];
return [[RTCSessionDescription alloc] initWithType:description.type
sdp:mangledSdpString];
}
@end